JSON Formatter, Beautifier & Validator – Free Online
Paste any JSON to instantly format, beautify and validate it. Syntax highlighting, minify option, tree view and one-click copy — all in your browser.
What Is the JSON Formatter?
The JSON Formatter is a free browser-side tool that transforms raw, unreadable JSON strings into properly indented, syntax-highlighted output. Validate structure on the fly, switch between 2-space, 4-space and tab indentation, minify JSON to reduce payload size, and explore the data with an interactive tree view — no server required.
Format minified or messy JSON with correct indentation and whitespace in one click.
Catches syntax errors instantly and shows exactly where your JSON is malformed.
Strip all whitespace for the most compact JSON payload — ideal for API requests and storage.
Explore deeply nested objects and arrays with a collapsible tree — great for large API responses.
How to Use
Paste Your JSON
Paste any JSON string into the Input panel — minified, partial, or already formatted. The tool accepts any valid (or nearly valid) JSON.
Beautify or Minify
Click Beautify to format with your chosen indent level, or Minify to produce the most compact single-line version for use in APIs or configs.
Check Validation
The status bar turns green for valid JSON or red with an error message pinpointing exactly where the syntax problem is.
Copy or Explore
Copy the formatted output instantly, or toggle the Tree View to inspect deeply nested objects and arrays interactively.
Frequently Asked Questions
No. All formatting runs in your browser using JavaScript. Your data never leaves your device.
Minify strips all whitespace and newlines, producing the smallest possible JSON string. Useful for reducing API payload sizes and storage footprint.
The tree view renders your JSON as a collapsible hierarchy of objects and arrays, making it easy to navigate complex nested data structures without getting lost in raw text.
JSON is a strict text format: keys must be double-quoted strings, trailing commas are not allowed, and undefined, functions and Date objects are not valid values. JavaScript objects are more flexible but not portable. This formatter validates JSON strictly according to ECMA-404.
Common causes include: trailing commas after the last item in an object or array, single-quoted strings instead of double-quoted, unescaped special characters inside strings, or missing colons between keys and values. The error indicator shows the line and character position of the problem.
2-space indentation is the most popular choice for JavaScript and JSON config files (used by npm, ESLint, Prettier defaults). 4-space is common in Python-adjacent tooling. Tab indentation is preferred in some Go and Rust projects. For API responses sent over the wire, use minify to save bandwidth.
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